Fully integrated High brightness (HB) LED driver solution

The Allegro MicroSystems A8511 Multi-output WLED/RGB Driver is a fully integrated high brightness (HB) LED driver solution for medium sized backlit displays. The flexible A8511 drive does not require an external power device to complete the backlight design standard. The A8511 integrates FETs for boost converters and four 150mA current receivers, providing a complete integrated solution at HB LED current levels.

When connected together, the device's LED channel allows a reception capacity of up to 600mA. The A8511 operates on a single power supply of 6.8V to 21V and can withstand voltages up to 40V. The operating frequency can be set to 2MHz to avoid interference with AM radio bands. The integrated boost DMOS switch is rated at 40V and 3.6A. PWM dimming allows the LED current to be controlled in a 1000:1 ratio. Additional 4:1 dimming can be achieved using the DIM pin.

The Allegro MicroSystems A8511 Multi-output WLED/RGB driver prevents short circuits in the output connector with an integrated output disconnect switch. Optional external thermiors limit LED current according to panel temperature, and the A8511 drive is mounted in a surface-mounted, 28-pin TSSOP package (suffix LP) with an exposed heat pad for enhanced heat dissipation. The unit is lead-free (Pb), 100% matte tin lead frame plating.

Features

● Four LED receivers rated 150mA(total 600mA)

● Boost converter integrates 40V DMOS switch and ovp load dump protection

● 600kHz to 2.2MHz switching frequency - Capable of operating above AM band

● Internal bias power supply for single-supply operation (V(IN)=6.8V to 21V)

● Turn off the current limiting battery leakage

● Active current sharing between LED strings is 0.8% current matching and 0.7% accuracy

● PWM dimming and LED PWM duty ratio control

● 4000:1 Dimming range

● Extensive failure mode protection schemes:

-   Short-circuiting LED protection prevents misconnected loads from being disconnected from the true output

-   Turn on the LED disconnect to protect LED faults

-   External thermistor induction limits LED temperature

-   Output overvoltage protection (OVP): 19.5V Adjustable to 38V by default

-   Turn on Schottky and turn on OVP resistance protection to prevent failure of external components

-   Input undervoltage and overvoltage protection against V(IN) changes (UVLO and OVLO)

-   Boost current limit, output short circuit limit, over temperature protection (OTP), soft start

Applications

● GPS navigation system

● Automotive infotainment

● Standby camera display

● Cluster backlight

● Portable DVD player

● Industrial liquid crystal display